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The conference proceedings of the first meeting on Catalysis of the Pedagogical and Technological University of Colombia are presented. This conference will be allowed in short time to potentiate the social appropriation of knowledge in this area of science at the regional level, providing opportunities for participants to present their work, and facilitating the dissemination of scientific knowledge. [ABSTRACT FROM AUTHOR]

In this work, the effect of the addition of iridium on TiO2 and Nb2O5 supports obtained by wet impregnation method was evaluated in the photocatalytic degradation of 2,4-dichlorophenoxiacetic acid under UV irradiation. The synthetized materials were analyzed by different techniques in order to determinate their physicochemical properties. In general, it was observed that the addition of iridium modifies the surface area, band gap energy and it enhances the crystallinity of the materials. Besides, an increase in the photoactivity in the degradation of the herbicide was evidenced using the materials modified. However, the Ir/TiO2 photocatalyst possess the best photocatalytic behavior toward the degradation and possible mineralization of the herbicide. The improved performance of the photocatalyst could be argued by the role of the iridium particles as electron collectors favoring the effective separation of the charge carriers and, as consequence, increasing the degradation of the molecule. [ABSTRACT FROM AUTHOR]

In this study it was evaluated the methylene blue degradation over TiO2 modified by sulfation and Au or Pt addition. These materials were synthesized by photodeposition method and then were widely characterized by different techniques. In general, it was found that Au or Pt particles size distribution can be effectively controlled modifying the deposition time. It was also found that metal particle size and dye adsorption on TiO2 surface, are important factors influencing the methylene blue degradation rate. The highest dye degradation was obtained on Au-S-TiO2 photocatalyst prepared by using 120 min of deposition time; the highest effectiveness of this material in the methylene blue degradation can be mainly due to a combined effect between the presence of gold nanoparticles acting as a sink for the electrons photogenerated during the catalytic reaction and the better adsorption of the dye over the S-TiO2 surface partially covered by gold particles with the largest sizes. [ABSTRACT FROM AUTHOR]

For this study were synthesized nanostructured materials of titanium dioxide by sol-gel method, at low temperature. The pH of gelation was set at 3 (TiO2-a), and 9 (TiO2-b), calcined at 500°C, to study the inluence of pH, in the electronic, optical, structural properties in the process of photodegradation. The results indicate that the semiconductors have particle sizes between 7 nm and 10 nm. The BET speciic surface areas of the samples are among TiO2-b 61 m²/g and TiO2-a 83 m /g higher than that of Degussa P25 titania (50 m²/g). The UV-vis spectroscopy of diffuse relectance was used to determine the (E ) bp band gap energy of the samples, where the values have the following order E bg (TiO2-a) < Ebg (TiO2-b)< Ebg (Degussa P25). The DRX indicate that the materials consist mainly of anatase phase. The TEM image shows that the TiO2-a presents smaller particle sizes (5 nm) compared to the other semiconductor. The photocatalytic activity for the prepared samples was tested in the 4-nitrophenol (4-NP) degradation. The mineralization of the contaminant up to 98% (TOC) was obtained with TiO2-a sample, exhibiting the highest photoactivity. [ABSTRACT FROM AUTHOR]

This paper proposes a new approach for estimating the radiant field in photocatalytic heterogeneous reactors. The effective radiation field model was developed from the constitutive equations for emission and absorption of energy. The new model considers five components for the radiation energy balance: i) The net energy flux in the volume υ, through α surface in the system. ii) The total energy is absorbed by catalyst particles. iii) The loss of energy is by scattering. iv)The gain in energy is by scattering (a phase function of the scattered energy is required) and the net energy flux in the volume is through the reactor surface. The model is an integro-differential unidimensional function in terms of an arbitrary nondimensional variable χ, where α(χ) is the surface area of the reactor, κυ, συ are the average coefficients of volumetric absorption and scattering, respectively. The model was used for the radiation field simulation with Six Flux Model (for CPC reactor and TiO2-P25). The model allows obtaining good results and is faster than the rigorous solution of radiation field. [ABSTRACT FROM AUTHOR]